Widely cloned, a Stanleyknife is approximately fifteen centimetres long, has a ridged slider on the top surface, by whose operation a triangular section of blade can be made to protrude from one end and lock in place. Stanley blades are extremely sharp and are double ended, being trapezoidal in shape.

As well as using reversible blades, there is a storage space for spare blades inside the handle, which is constructed of two die-cast sections of steel secured together with a single large screw.